THE WAVELENGTH DISPLACEMENTS OF SOME INFRARED LINES BETWEEN LIMB AND CENTER OF THE SUN. II

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Abstract
The differences between the wavelengths at the solar limb and at the center of the disk have been measured for lines of Fe I, Si I, and Ca II in the λ8500 Å and λ8900 Å regions of the spectrum. The values of the limb–center displacements (in km/sec) of the Fe I lines in the two wavelength regions studied are found to be the same as those obtained by M. G. Adam for neutral metal lines at λ6100 Å. The limb–center displacements of the Si I lines are similar in magnitude and in the same direction as those of Fe I. Although the data are insufficient to decide the question as to term dependence of the solar wavelength shifts of Si I, any relation to the shifts observed in a laboratory light source can be excluded. For the Ca II lines at λ8500 Å and λ8900 Å, corresponding to two different transitions, the limb–center displacements differ from each other both in magnitude and in direction. The limb–center displacements of the λ8900 Å Ca II lines are smaller than those of the Fe I lines, while those of the λ8500 Å Ca II lines are significantly larger and in direction opposite to those observed for lines of Fe I.Where possible, comparison has been made between the wavelengths observed at limb and center of the disk and the solar wavelengths predicted by General Relativity Theory. In all cases the wavelengths at the limb were found to be closer to the predicted values than the wavelengths measured at the center of the disk. While for the lines of Fe I the predicted solar wavelengths and those observed near the limb (r/R = 0.982) are in good agreement, the wavelengths close to the solar limb of the λ8500 Å Ca II lines are found to be significantly larger than those predicted by relativity theory.

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